


Heart Flutters

by Lingeringchaos, ZionKilse



Category: Undertale (Video Game)
Genre: AU Shenanigans, Alternate Universe - Maniatale, Alternate Universe - Swapfell (Undertale), Alternate Universe - Underfell (Undertale), Alternate Universe - Underswap (Undertale), Angst with a Happy Ending, Bad relationship is bad but good relationship is good, ClassicBBQ, Creepy, Domestic Violence, Emotional/Psychological Abuse, Eventual Romance, Fluff and Angst, Fluff and Humor, He needs love, Healing, Healthy relationships after Unhealthy Relationships, M/M, Maniatale Sans - Freeform, Physical Abuse, Recovery, Swapfell Papyrus (Undertale), Swapfell Papyrus/Classic Sans, Swapfell Sans (Undertale), Swapfell Sans/Classic Sans, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underswap Papyrus (Undertale), Underswap Sans (Undertale), Undertale Monsters on the Surface, Violence, all AU's on one surface, monsters are all on the surface, regular fellverse violence, rottenjoke - Freeform, save the boi, surface AU
Language: English
Status: In-Progress
Published: 2020-08-24
Updated: 2020-08-30
Packaged: 2021-03-06 19:55:40
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 8,787
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26074525
Author URL: https://archiveofourown.org/users/Lingeringchaos/pseuds/Lingeringchaos, https://archiveofourown.org/users/ZionKilse/pseuds/ZionKilse
Summary: Sans has a secret admirer, just who could it be? Sans aims to find out who keeps sending him beautiful butterflies.
Relationships: Papyrus/Sans (Undertale), Sans/Sans (Undertale)
Comments: 25
Kudos: 30





	1. Beautiful Butterflies

**Summary for the Chapter:**

> Sans doesn't know where or who sent these little notes, but they've got him all kinds of flustered and feeling good about himself.

**Notes for the Chapter:**

> Cover by this lovely bean! https://mobile.twitter.com/AcidBunny0
> 
> Chaos: Welcome to our fic, please enjoy your stay!
> 
> Zion: This fic was inspired by a friend's artwork and further talking of the piece resulted in yet another fic on our list. But boy is it a tasty one.

Sans sighed rubbing at his face, fighting to stay awake. The teacher's monotone voice was making him sleepy, it didn't help that he was next to the window. The warmth of the sun only made him sleepier, he could use a nap right about now. He glanced down at his notes with a grimace, he'd written his name. That was a start, right?

A small origami butterfly landed on his desk, carefully folded wings fluttered as traces of lavender magic drifted off before dissipating. Somehow no one seemed to have noticed it either, Sans glanced around and it didn't seem to him like anyone was looking at him. Gingerly he picked it up and looked it over, he could see what looked like writing on one of the edges. A note? He looked around before carefully unfolding it, spreading the small paper out.

Inside the paper was a neatly written note, he looked around and when he saw no one was watching to rat him out he started reading.

_Sans,_

_I don't know what you're doing in this class, you're leagues smarter than this incompetent professor. But I'm glad that you are here, you actually make this class worth coming to. The face you make when you're sleepy is unfairly adorable._

The end of the note had a ketchup packet taped to it but no name.

Sans blushed a deep indigo, his white eyelights darting around the many monsters and humans among the class. Still none stood out to him, who was the sender? They could only be a monster, humans no longer had real magic. His eyelights scanned the monsters in the class, two skeleton monsters, two bear monsters, one fish monster, and several dog monsters.

He carefully refolded the butterfly and pocketed it for safekeeping, maybe it would help him find the secret admirer.

It was then he noticed the eyelight of one the skeleton monsters watching him. White eyelights looked away, the tall thin looking skeleton seeming to retreat into his fluffy hood, but not before Sans saw a scar over his left eye. He was a fell monster, then, a Papyrus type certainly, but, Sans’s brother would never slouch like that.

Next to him was what could only be his brother, an angry looking Sans type who gave his brother a look and pointed down at the paper as if telling him to focus.

The Papyrus mumbled something, his long fingers picking up a pencil, scrawling messy notes as he looked up at the professor. Once his heated brother turned away, he put the pencil down, leaning back in his chair, relaxing.

Only for his brother to jab his ribs and tap the paper again, squinting up at him.

A low grunt left the skeleton, and he sat straight, returning to his note-taking. Clearly a switched pair of brothers.

The sans type squinted at his tall brother for a while as if to make sure he was taking his notes this time, but he accidently caught Sans's gaze too.

Sans took in the other Sans's features, lavender eyelights, three scars over his left socket, sharp fangs. Tattered band shirt and a blue bandana, he looked like that guy girls were told they weren't allowed to date but did anyways.

The skeleton looked away, sticking his nose in a book a moment after their eyes met. Scowling into the book Razz didn't dare look again, lest the others see him blushing like some kind of high school teen.

Sans sighed, fingers gently touching the secret note a slight blush still coloring his cheekbones. As long as the secret admirer wasn’t Jerry, he was excited and curious to find out who it was.

But who to ask first was the question, for all he knew the other two skeletons had seen the note come to him and looked at him when he'd looked at them. And that was probably just a coincidence, right?

There was really no proof it was either of them. He looked around the room again, but no one was meeting his gaze.

He guessed he would have to just ask around, see if anyone knew who had sent it or had an idea at the very least.

Once class mercifully ended, several of the students quickly fled, as if hell itself were on their heels. The Sans type skeleton went to the professor to ask a question and the tall Papyrus type was suddenly next to him.

"You're in my history class, aren't ya? In an hour? I’m Slim. Ya wanna stop at the dining hall and grab some coffee with me?"

Sans was half certain he'd just teleported across the room, he blinked owlishly at him. As smart as he was he didn't excel in social graces. Sans's mind stalled from the sudden invite, he stared at the taller skeleton like an idiot for what felt like forever until-"Papy come on!"

Razz called his brother, hands on his hips as he tapped his foot impatiently.

Sans shook his head and glanced at Razz. "Uh...Slim, right?"

“Yep.” Slim said, with a shy smile. “What nickname did they give you?” 

"Oh, uh no nickname. Just Sans." He chuckled softly.

"Papy! Hurry up!"

“Oh! Lucky..” Slim winked and he sighed. “Well, raincheck? Catch ya later. Comin’ bro.” He said before following his haughty brother.

"S-sure." Sans waved as the two brothers left, he grabbed his own stuff and headed out. Maybe Blue would have an idea, he seemed to know almost everyone here somehow.

He found Blue in the cafe, drinking a frappuccino which would surely have Stretch cursing out every barista that worked here. Blue’s eyelights were stars as he drank the delicious caffeinated treat, and flirted to the cat girl next to him.

"I'm telling Stretch you have that." Sans told Blue the moment he saw what he had.

“No one likes a killjoy, Sans.” Blue sniffed, before grinning. “Besides, he _loves_ when I’m extra caffeinated! It’s the only time he ever lets me clean that pigsty of a nightmare he calls his dorm room.” Blue made a face. Stretch’s roommate was just as lazy and unkempt as he was!

"Oh fuck. Who's the new guy who gave Blue coffee?!" Salt groaned upon seeing him with it in hand, already turning to flee. "Sorry Sans, I'll be sure to attend your funeral."

“It won't be that bad!“ He hoped, the last time Blue had gotten a coffee, he’d come home to their dorm room with a sock on the doorknob. Along with three different monsters climbing out his dorm window, not to mention the mess. Sans shuddered slightly, who would have thought someone so clean could make such a filthy mess?

"I don't wanna be around when it hits his mana lines! Not after last time! I like walking!" Salt retorted before darting off.

Sans snorted and eyed Blue warily, Salt made a very valid point. Perhaps Sans should plan to be away from his roommate for the next twelve hours at least.

He didn't want to limp out as he'd seen Salt do after all. But he still needed to ask about this mysterious note! 

"Blue, have you ever seen anything like this?" Sans asked, drawing the paper butterfly out of his pocket and holding it out to Blue in his open palm.

Blue leaned forward to look at the paper and his eyelights sparkled with excitement, someone finally made a move on Sans? It was about time! "Can't say I have. What is it?"

“Dunno, it flew to me during class.” Sans said, scratching the back of his skull. “It’s um...a note.” Sans cursed his cheekbones, knowing they were glowing.

"A note huh? What about?" Blue leaned forward, chin resting on his fist as he grinned broadly at Sans.

“N-none of your business!” Sans said quickly holding the precious butterfly note to his sweater.

"Aw c'mon Sansy! I won't tell!" Blue gasped making puppy dog eyes at Sans.

Sans squinted at the taller, immune to his puppy dog eyes. “Like you didn’t tell anyone about the experiment I was working on?”

"That was a public safety concern!" Blue defended looking taken aback. "Someone could have gotten hurt!"

“You didn’t trust me to handle it with care.” Sans crosses his arms. “So how can I trust you to handle this with care?”

"Sans you put a hole in the wall and nearly dusted someone!" Blue pouted. "And why would I tell? It doesn't benefit anyone."

Sans sighed at this, Blue had a point. His science experiment had gotten a _little_ out of hand. It was just so relieving to be passionate about something again. In the underground, he’d stopped dabbling with science all together. He was finally finding joy in it, hope for life. It was refreshing and got him excited, possibly a little over zealous too.

“I-I guess…” Sans said shyly before hesitantly opening the note for Blue.

Blue scanned the note over and his eyelights sparkled as a giddy grin spread across his face. "Aw Sans! Looks like you've got an admirer!" He said softly but the excitement was dripping from every word. "No idea who it is?"

“Not really.” Sans admitted, rubbing the back of his skull. “I looked around but, no one really made eye contact…” 

"Hmmmm, I'll see what I can dig up for you Sansy, but! You have to give me something too." Blue grinned deviously.

Sans frowned glancing at Blue. This bode unwell. “What’s that?”

"I want the key to the planetarium." Blue almost purred, tapping his gloved fingers together. 

Sans gave his much taller double a quizzical expression. What did Blue want with his key to the planetarium? 

Professor Swell had given it to him so he could come in and help grade papers, but if he were honest he mostly used it to nerd out and look at the stars. 

“Sure, but, I want it back in a week. Got a job I might actually have to do if the professor doesn’t lose the papers he needs grading - again.” Sans said. 

"Deal." Blue giggled his eyelights pentagrams.

“... Just what are you planning?” Sans said, handing him an old fashioned steel key. He knew Blue wasn’t going to break something, or trash the place, Blue would never do that, but those pentagrams boded unwell. The last time he’d seen them was when he'd seen the sock on the dorm handle.

"Just a date, no big deal." Blue chuckled.

“Ah.” Sans chuckled. “Go easy on the little guy.” Sans said. He was quite certain Salt hadn’t walked straight for a week! 

"I didn't do anything to him he didn't like!" Blue pouted. "I wish he'd let me tell everyone."

“Not sure why he doesn’t.” Sans said. “Then again he’s kind of a private guy.” Sans mused. He hardly knew anything about Salt despite knowing him for a year now.

"He's just shy, but I'll get him out of his shell!" Blue beamed.

“Heh, I’m sure you will.” Sans said with a grin. If anyone could, it’d be Blue. Afterall Blue was the one who helped him even apply for a degree.

"I'll get right on digging up who sent you that Sansy, no worries!" Blue giggled.

“Okay...just be discreet about it?” Sans said with a frown. Maybe this was a bad idea. Now he was envisioning Blue boldly and loudly interrogating all of his classmates.

"I will! I'll just ask around!" Blue smiled.

“Wait, Blue that’s really direct!” Sans said, his eyelights shrinking.

"I wasn't gonna mention your name silly." Blue giggled. "Just if anyone has seen a monster sending little paper butterflies."

“I- well… I guess.” Sans said shyly. “I just…” He didn’t want whoever sent the note to be scared off. . . but Sans really did want to know who it was. Who on earth would think he was special enough to go through this kind of trouble for?

"Don't worry Sansy! I'm on it! But first-I need to take care of a small thing. But don't you worry! I'll do my best!" Blue stood up suddenly nearly throwing the table across the room.

Sans didn’t so much as blink, it seemed the caffeine was finally having its effect on his overactive roommate. At least there had been no drink casualties yet. The last time Blue had moved so fast, drinks and plates had gone flying.

"Cya tonight!" Blue giggled before running off, cackling as he went.

Sans watched him go rubbing the back of his skull, what had he just unleashed on campus? Well, that wasn’t his problem. He stuck his hands in his shorts pockets, ordered a muffin and a coffee from the cafe. He made his way to his next class, human history. A mandatory class to catch all monsters up and Sans’s guilty pleasure. He’d thought he’d hate it, who wanted to learn about humans? But, it was fascinating, in a way, all the ways humans self sabotaged their societies and put themselves technologically back by theoretical centuries. The tall skeleton with the white eyelights was already there, leaning his chair back, feet on his desk.

"Oh, hey Slim." Sans greeted. "What's up?"

Slim looked over and grinned lazily. “Ceiling.” He pointed up.

Sans snorted softly and shook his head. "Okay, smartass. I mean what's going on and you know it. You wanted something earlier?"

Slim blushed purple and scratched the back of his hoodie. “Uh… yeah, I was gonna ask if you… wanted to grab something to eat after class.” He said shyly.

"Oh! Sure, I don't have any plans." Sans chuckled, that was something he did like about college. It was easier to find friends with similar tastes to his own. Well, except for Blue. Blue wouldn't take no for an answer, and they were roommates.

Slim smiled brightly. "Great!"

"Where at? I gotta drop my stuff off at the dorm but after that I'm free for the rest of the day." Sans said as the rest of the class filed in.

"Could meet at the dining hall, there's a lot of choices there." Slim mused.

"Sure thing. Cya there." Sans smiled before going back to his seat beside a rabbit monster. The professor wasn't there as of yet, so he pulled out the note to look at it again. Who could it be…?

***

Sans dropped his belongings off at the dorm, he didn't see Blue around so he was probably still working off the caffeine. He headed to the dining hall and looked around for Slim.

Slim was outside the front doors, fiddling with a rubix cube. He looked up and smiled at Sans and waved, pocketing the cube.

"Heya Slim." Sans smiled as he waved back, approaching him. "So, coffee?"

“Sounds good.” Slim said, opening the door for Sans as the two walked into the large campus building.

"Thanks big guy." Sans chuckled heading to the counter so they could look at the menu. "So, I hadn't ever seen you and your bro before. You guys just move here?" Okay well he'd seen them all this last term but not before that, he hadn't talked to either one up until now.

"Yeah. Took a while for our verse to get the greenlight to go out and about in the community." Slim made a face.

"Just a regular fellverse though, nothing special. Just our queen and judge are a little unhinged." Slim winked, looking over the menu.

“Heh, I don’t see the issue, Red and Edge didn’t have too much trouble. And you seem alright to me.” Sans replied easily, he was kinda like Red right? Red looked tough but he was too nice for his own good at times.

“Thanks.” Slim said with a smile. “Humans just being cautious I think.” He shrugged. “Know what ya want?”

“Yeah, I think I’ll get a vanilla latte.” Sans hummed.

“A mocha frappuccino, with whipped cream.” Slim said brightly.

They put in their order and went to stand over by the counter to wait for it. “So, how’s life on the surface been?” Sans asked looking up at Slim, damn was he tall. Even Papyrus and Edge were shorter than this guy.

“Weird.” Slim admitted. “In a lot of ways… I know its stupid, but I miss the underground.” Slim admitted. “I don’t really trust humans. They make me antsy. But. . . The sky, the stars, the sun, that’s all nice.”

“You’ll get used to them, they ain’t that bad once you get to know’em.” Sans assured with a grin.

“Yeah?” Slim said. “Guess you’re right, they’ve been welcoming at least.”  
  
“Mocha Frappe and a Vanilla Latte!” A bunny girl called, pushing out their two drinks. 

“Thanks.” Sans took the cups and offered one to Slim.

Slim smiled and took his, they two sat down together at a booth. “How long have you been on the surface?” Slim asked.

“Few years now, it’ll get easier the more time you spend up here.” Sans said as he sipped his coffee.

Slim nodded. “Yeah, guess so. We haven’t been up here very long. Six months before they released us, my bro and I decided college would be a good idea, especially since it's free for monsters.” 

“Yeah, we got a lot to catch up on.” Sans chuckled softly. “We’re behind and the humans here are pretty nice too.”

“That’s good.” Slim gave a sigh of relief. “They seem nice, guess I’m just, slow to trust.” He gave Sans a shy look. “You don’t seem very behind...you’re probably the smartest in our class.”

Sans flushed and rubbed the back of his skull. "Uh-well, bout that...uh, only certain subjects. Red, Stretch and well, everyone is the top in something or other."

"Don't shortchange yourself. Just because you're not the only genius doesn't mean ya ain't a genius." Slim winked. “From one self loathing genius to another.”

Sans snorted into the foam of his latte and chuckled. "Alright, alright. You make a fair point, but it's true, we're among others like us now. You should see Stretch, bastard can fix anything."

“Heh, I think I know who you’re talking about. He’s seeing my bro’s roommate. Smart guy.” Slim agreed, giving his mocha a delighted look as he sucked it down. “But you know your physics like nobody’s business.”

"What about you though, what's your thing?" Sans asked laughing softly. "I know Edgelord though. Jock from hell I swear."

“Eh, I'm more of the experimenting science type, and yeah he is.” Slim snorted. “He doesn’t stay still!”

"Oh yeah? That's cool. Hah, tell me about it. He and my bro are always competing." Sans laughed. "It's fun but tiring to watch."

“Yeah, watching my bro is exhausting. He’s full of energy.” Slim said with a fond smile. “Guess all the switched Papyruses are like that.” He said to himself.

"You're the switched one!" Sans laughed.

“No, you are!” Slim stuck out a purple ecto tongue, covered in whipcream from his coffee. “From my perspective, all Papyruses are the older brothers and Sanses the younger, more energetic ones.”

"You got it backwards! I'm older and my bro is younger." Sans retorted easily giving Slim a confident look.

“Yeah? That's why you're the switched one.” Slim said with a mischievous grin. 

"We're gonna have to agree to disagree or this'll never end." He snorted.

“Guess so.” Slim snickered, eyelights sparkling in amusement.

"What's your favorite class so far?" Sans asked, gulping down his latte. 

“Anatomy!” Slim said brightly. “Humans are so disgusting, did you know they’re full of organs? But it’s cool learning about them and monsters on a cellular level, seeing how everyone ticks.”

Sans couldn't help but snort, shaking his head. "I do know, but I don't take anatomy. Not really my thing, you know?"

“Yeah, you’re more into space and all those complex theories and string theory, right?” Slim asked. “Really cool.”

Sans smiled and nodded, setting his cup down on the table. He just happened to glance at his watch, holy shit they'd been here for over an hour! "Hey Slim, I'm enjoying our chat but I gotta get going now. Homework and all that."

“Oh, man, yeah.” Slim said, glancing at his phone. “Didn’t realize we were here so long! Thanks for hanging out.” 

"You too, it was nice." Sans chuckled standing up, he stretched with a groan, his spine popping. "Thanks for inviting me."

“Had a lot of fun.” Slim scratched the back of his skull. “See ya soon?”

"Yeah, we got class tomorrow." Sans reminded, with a friendly grin.

“Right.” Slim laughed. “Cya tomorrow then.” He said with a wink before shortcutting away. He appeared from the void down one of the long winding paths of the campus. The path was empty and coated in colorful fall leaves. Slim lit a cigarette, his white eyelights flickering to purple as he blew out a small plume of smoke. 

***

Sans headed back to his dorm and-judging from the sounds he was hearing Blue had a visitor.

"You can't leave! We only had three rounds!" Blue wailed mournfully.

Only three?! Sans did not envy whoever he had in there with him! He tried to quietly creep past Blue's room to his own room. He was already well aware of Blue's libido and didn't want to be involved, he prayed for the poor monster in his clutches while high on caffeine.

“Sans! Is that you?” Blue energetically kicked open his own door, peering out, eyelights in the shape of baby blue pentagrams. “I need some whipped cream, stat!”

"W-whipped cream?" Sans stammered caught off guard. "I-uh-fridge?"

“Toss it to me. I can’t let him escape.” Blue said firmly, some muffled cries came from Blue’s room. “Don’t worry, he’s fine. He has a safe hand movement!”

"Uh-Blue? Who are you holding hostage and why?" Sans inched away, he could pay the price of whipped cream to avoid getting caught up in Blue's wild play. Last time he'd had a few monsters involved.

“Salt, and because he asked me to.” Blue said sweetly, the muffled grumblings coming from the other room suggesting otherwise.

"Sans!" Salt called from Blue's room. "If I dust here, kill the new barista!"

Sans snorted. “I”ll just have them name a drink after ya. The pounded to dust sound good?” 

"I'm kicking your ass later for this Sans!"

“Good luck reaching it, half pint!” Sans called back, handing Blue the whipped cream. He would be regretting teasing him later, he was sure, but he couldn’t resist!

"Blue untie me! I need to break his kneecaps!"

“No, no, no.” Blue said shaking the can of whipped cream. “First I want to make our guest lick this off your pubic bone!” 

“Me?” Sans demanded eyelights shrinking.

“No, I have another guest gagged in there.” Blue said brightly.

"But then he'll get away! Blue! I'll come back!" Maybe.

“You can adorably try and break Sans’s kneecaps later.” Blue said. “Thanks Sans!” he shut the door, the sounds becoming muffled, fortunately for Sans and his decaying sanity.

Sans sighed and went to his own room now, hadn't Salt run away earlier? He shook his head and went to his desk, may as well get some work done.

Sans opened his text book with a sigh, a small origami butterfly fluttered it's glittering wings as he did so. Another note inside his text book!?

It gently beat it's little wings landing on the back of his hand and going still.

Sans smiled at it, admiring the intricate lavender wing design. It was so beautifully made, the magic he could feel from it was so gentle.

The delicate origami butterfly crawled across his hand and to his palm before the magic faded away entirely.

Sans looked around for a note, but this time there was none, just a beautiful display. He hummed dreamily, wondering who was putting so much effort into these little creations? And more importantly, who thought he was worth that? And did Blue find anything out?

Of course, he would be waiting until tomorrow to even ask Blue. Not about to set foot in that room until he knew for damn certain Blue had his fill.

With a sigh, Sans turned to his homework, focusing on the complex equations in front of him, letting his mind relax into the science. His little butterfly companions sitting on his desk.

***

When Sans went to his desk the next day he was pleasantly surprised to find another butterfly waiting for him, and this time it was a note again! He couldn't help but feel a little giddy, his cheekbones a deep blue as he sat down and carefully scooped it up to open it.

_Sans,_

_There is to be a meteor shower tonight, humans say they're rare and beautiful occasions. Perhaps I will see you there, outshining every star with your radiance. No shower of stars could compare to one as beautiful as you._

Sans blushed so bright, he was certain that Blue would see a glow through their walls. What beautiful lies his admirer had written. Still, it touched him, making his soul flutter in his ribcage.

He was almost skipping through the dorm room that morning, barely able to contain himself. These little notes, they made him feel special. In a way that no award or trophy given to him for his knowledge ever could.

“Someone had a good night.” Blue said, greeting Sans as he walked in their little kitchen, Blue making pancakes. “Was the homework that good?” 

Sans blushed more and rubbed the back of his skull. "Oh-uh, I got another note this morning." Sand explained shyly. "Am I that obvious?"

Blue grinned, eyelights turning into stars. “You did!? That’s adorable!” Blue said, vibrating with excitement.

"Y-yeah, it's uh...really, dumb but…" Sans showed him the note. "Can you believe that? They gotta have a screw loose."

Blue gasped, his own cheekbones flushing a light blue. “Sans! This is precious! This person really cares about you, to see how amazing you are! I’m so happy someone is finally recognizing your magnificence!”

"Wh-what-no-Blue!" Sans tucked the note away and covered his face, he wasn't any of those things!

“Yes! It’s high time someone saw you for what you are and made a move!” Blue said firmly, flipping one of the pancakes too hard and frowning as it stuck to the ceiling. “Hm.” 

"But-" Sans began to protest.

“No buts!” Blue waved his cooking spatula at him as the pancake slowly peeled off the ceiling and landed on his skull. Blue made a face, tossing the offending hat into the trash.

"Aw, I liked your new accessory." Sans snickered despite his flush. "I guess you could say-"

“Don’t you dare!” Blue said, sensing a pun.

"It's in good taste!"

“Saaans!” Blue groaned as if physically pained.

“Out, out, out!” Blue chased his roommate with his spatula, as Salt staggered to the door, rope around his ankles and wrists, making him have to hop around like some strange bunny.

“Salt Serif! You haven't eaten breakfast yet!” Blue stopped his chase of his roommate to hollar at his fleeing captive.

Salt froze like a deer caught in headlights. "But I-"

Sans took the chance to steal a plate of breakfast and bolted out the door, shutting it behind him. Shaking his head he headed to a nearby picnic table to eat, the sun was just peeking over the trees, morning dew was still lingering on the grass and flowers.

Sometimes Blue could be an overwhelming roommate. He did not envy Salt, or whoever else Blue had had tied up in that room. At least Blue kept things interesting. 

Plus he could cook really well, it was nice. He poured some ketchup next to his hash browns and began to eat watching the sun slowly rise higher. He couldn't help but think of the butterfly notes, he needed to find out where they came from. Blue didn't seem to have any answers yet.

As he ate his breakfast, he watched monsters slowly come from their dorms, sit at the picnic tables around him, rush off to an early class or the dining hall. It was peaceful, and still warm enough to go outside with just a sweater and enjoy the campus. 

Slim caught his eye, the skeleton was lethargically walking up the hill, following his brother, the big guy seeming half asleep. 

Chuckling he waved to Slim, the poor guy looked ready to fall back asleep. His brother must be an early riser like Papyrus, Edge and Blue.

Slim gave a lazy grin and a wave, followed by a long yawn. Razz glanced at Sans and gave a small nod, before saying something to his brother, likely telling him to hurry up.

Slim seemed to sigh and he did hurry up, even with his long stride Razz was still faster.

Slim looked back at Sans as they hurried past, offering him another smile. "Hurry up! We'll be late!" Razz huffed.

"M'comin!" Slim sighed slinking after his brother, hands in his pockets but not without a wink to Sans first.

Sans smiled watching the two walk off. He supposed that meant he better get moving to class too. But not before he finished his breakfast.

***

“Work wants me.” Slim tapped his brother on the shoulder, half way through their shared psychology class. To which Razz made a sour face, how dare they call him during class!

“Doesn’t she know you are trying to get an education!?”

"She don't care ‘bout that an’ you know it bro." Slim retorted, and it wasn't like he didn't enjoy it. The education was more to appease his baby brother, and keep an eyelight on him.

"Well you're not going in the middle of class!" Razz squinted at Slim, as if daring him to argue.

“Can’t disobey the queen, m’lord.” Slim said with a grin and a wink before disappearing with a soft pop. He was certain his brother would rage at him later, but duty called. Just, not the one he told his brother he was doing. The queen was more than happy to oblige his school hours. No, this was some light recon. 

He shoved his hands in his pockets, making his way into Sans’s dormitory, looking for his room number. It wasn't hard to find and he soon spotted it, he listened quietly. Didn't sound to him like anyone was inside, perfect.

He easily picked the lock with a thin bone attack, walking into Sans’s shared dorm.

He opened the first door off of the main room, raising a single brow bone at the length of rope on the floor and cuffs hanging off the walls. Probably not Sans’s room, had to be his dorm mate's.

He went to the second room opening it. Ah, ha. This room was much less curious, an unmade bed, books strewn about, some bottles of ketchup. Clearly this was Sans's room, only a switched Sans had a room this messy. Now then, time to get to work.

Slim opened his backpack, taking out his surveillance equipment. He put several tiny ‘bugs’, cameras with microphones around the room. One was placed carefully in a picture frame of Sans and his brother, one in the light on the ceiling, one in the corner of the window, and one behind Sans’s monitor for his computer on his desk.

That would make it easier to learn more about his new friend, he was very curious about Sans. There was just something about him that drew the attention, but he couldn't put his finger on it. Slim hummed in thought as he began to carefully go through Sans’s things, making sure to put them back where he found them.

Photos, class notes, past tests, kind of what he'd expected actually. Nothing out of the ordinary so far. Just seemed like a regular switched Sans, with a regular interest in school. So what about him was so interesting? Slim wanted to know, he _had_ to find out. 

Slim was going to find out, one way or another. He’d already gotten Sans to hang out with him, with very little effort. The guy seemed lonely, that just made this process even easier. Now that the cameras were in place, he’d monitor him, see what secrets this Sans had tucked away. Slim would learn _everything_ there was to know about Sans, from his favorite food down to the way he folded his clothes.

After all, everyone had skeletons in their closet. And he would unearth them all.

**Notes for the Chapter:**

> [Slim's](https://soundcloud.com/colddriven/cold-driven-the-wicked-side-of?ref=clipboard) got an socket on Sans, and maybe a few cameras too.


	2. A Chance Meeting

**Summary for the Chapter:**

> Sans gets another note from his secret admirer and reluctantly shares their existence with his friends.
> 
> AKA the one where Blue has some questionable reading material.

**Notes for the Chapter:**

> Thank you all for the kudos/comments! <3 We love them and are so glad people are enjoying this fic!

Sans was only a little late to his first class and somehow managed to stay awake through it. His second class was one shared with the brothers and he smiled and waved at Slim who was being scolded by Razz outside the classroom door as Sans walked in.

“-can’t just leave class like that!” Razz huffed and glanced in Sans’s direction as he waved. He turned his gaze back to Slim and scowled. "Look at me when I talk to you! You can't just leave class like that! We're trying to improve our quality of life and you just run off to do- whatever it is you do for the Queen!"

Slim had cast Sans a smile and a wave back and turned his attention to his brother upon being told to. "But bro, it was important."

"No! It was not so important that you missed the entire last half of our class!" Razz stomped his foot, hands clenched at his sides. "If this happens again I am speaking to the Queen about terminating your contract with her!"

Slim pouted at that, shoving his hands in his pockets. "But bro, it's good gold-"

"I don't give a damn how good the pay is! This is your education! You will take it seriously!" Razz cut him off growling lowly. "Don't fucking do it again! I mean it! I will terminate your contract!"

"Okay, okay! I won't!" Slim said, putting his hands up in a gesture to placate his furious little brother.

"You better not!" Razz snapped at him, glare harsh. With this he went into the classroom, glancing at Sans who felt like he'd just eavesdropped on their private conversation.

"H-hey…" Sans rubbed the back of his skull shyly, feeling so very awkward all of a sudden.

"Hey. Sorry ya walked in on that." Slim said wringing his hands. My bro can be a lil' hot headed. He takes education very seriously, but, I'm kinda a slacker." Slim grinned. "Must be a not switched Papyrus thing." Slim winked at the smaller skeleton.

"Heh...I mean, I get where he's coming from. It's kind of important, and he cares about you if his anger is anything to go by. Ya know? He's uh, just like my bro. He just wants the best for ya." Sans chuckled smiling at Slim. "He's just looking out for you, and you  _ are _ a switched Papyrus."

"Yeah, I know." Slim's features softened. "He's the best bro I could ask for. I wish I didn't disappoint him so much…" Slim confessed, looking insecure. "But I'm trying to stress him less, don't want him losing his Sansenses."

Sans couldn't help but snort at this. "Well that's a new one for me, when we got more time I'd love to exchange puns with ya big guy." Sans winked at Slim as he passed him. "Better do your homework, or your chances will be slim to none."

Slim chuckled at the pun, white eyelights lighting up in amusement. “That’s true, he’d really take me to class.” 

“Cya after class?” Sans replied easily before heading back towards his own seat before the professor got there.

“You bet.” Slim said following him in, seating himself besides his still livid brother, taking out his binder and notebook with a sigh. This was going to be a long class.

***

Sans sighed as he entered the dining hall. He had about a half hour before his next class, maybe he could find Blue and see if he had any leads on his mysterious note sender? Blue should be free right now, they usually ate lunch together on Tuesdays, but he was nowhere to be seen. 

It was unlike him to be late and he wasn’t in any of their usual spots in the large cafeteria. He went to the burger section, grabbing burg, hot dog, fries and a drink, lunch of champions and all payable by a little card the underpaid cashier swiped. He looked around, carrying his lunch, doing one more sweep of the area in case Blue was hidden by the usual rable of monsters and humans in the dining hall, yet there was no excitable and overly horny roommate to be found. Sans frowned at this.

At least, until a butterfly note landed right between his sockets. The magic tickled his face and he couldn't help the small giggle that escaped him.

Gingerly he cupped the delicate paper insect and pulled it away from his face, looking down at it in his palms. "How do you keep finding me anyways?" He asked it before using one hand to grab his phone, putting it between his skull and shoulder after dialing Blue’s cell phone. Using his now free hands to unfold the new note.

_ Sans, _

_ Are you going to see the meteor shower tonight? If you are, I want to meet you there. I'll be waiting by the large oak tree, I hope to see you soon. I hope you are as excited as I am to meet. _

Sans blushed brightly, soul pounding in his ribcage. They wanted to meet!? Tonight!? He knew the spot the note was talking about. Senior hill was the best place to stargaze, complete with telescopes provided by the university. Sans didn't know it but he'd gained the attention of several monsters and humans around him who watched him and his beautiful note curiously.

"Sans?" Blue answered his call.

Sans jumped at Blue's voice, completely flustered and distracted. He had forgotten he was calling his roommate. "H-hey, you still coming for lunch?" Sans asked.

"Oh-! I'm at our spot already silly!" Blue giggled. "Come on!"

Sans frowned looking around the dining hall. He most certainly was not! Unless Blue meant outside? "Outside?"

"Yes, outside silly! It's such a nice day out!" Blue laughed. "Why wouldn't I be outside when the sun is shining and the sky is so clear! We're looking at clouds too!"

"We?" Sans asked, carrying the rest of his lunch out and walking to their usual picnic table.

"Hi Sans!" Blue hung up the phone and waved excitedly at him. Red, Stretch and Toffee were sitting with him too. Red was as close as he physically could be to Toffee without actually touching.

They had a blanket laid out over the grass where Blue was on his back looking at the sky, Stretch was right next to him nearly asleep in the afternoon sun.

"Hey!" Sans greeted, sitting down with them. "The matter, Stretch? Did you red too much in class? Blue a fuse in that big brain of yours and now you can't stay awake? Seems like you need some toffee." 

"Saaaans!" Toffee scolded, squinting at him like only a Papyrus could.

Sans's perma grin stretched wider and he winked, seating himself next to Blue. "Did your victims make it to class okay?" He asked his roommate.

"Victims?" Blue blinked at him. "Why, whatever do you mean Sans?"

“Salt and whoever else you had tied up in your room this morning.” Sans teased, taking a bite of his burger. “Or did they skip class to lick their wounds?”

"Don't be silly Sans! I didn't have anyone tied up in my room!" Blue snorted, but the look in his eyelights told Sans to shut the fuck up.

Stretch who had been for all intent and purposes asleep, cracked a socket open. “Blue’s way too busy to be fooling around like that, right bro?”

"Of course Papy, you know I'm working hard to get through all my classes!" Blue beamed. And he did, but that didn't mean he didn't make time for extra activities.

Stretch closed his sockets again and Sans snorted. Stretch knew very well about Blue’s extra curricular activities! Or at least the ones involving Salt. Now Sans was curious about the other unnamed monster Blue had been spending time with.

"So, Sans, any more notes?" Blue grinned devilishly at him, throwing Sans under the bus for his treachery. Sans squeaked, eyelights shrinking. That traitor!

"Notes?" Red asked, leaning forward in interest.

"Sans has been getting notes from a secret admirer!" Blue giggled his cerulean eyelights the shape of pentagrams. "It's so cute! They're little butterflies!"

“Butterflies?” Stretch asked curiously, sitting up. “I want to see!”

"You'll have to get them from Sansy." Blue purred silkily.

“They- they’re private!” Sans said blushing, his eyes staring pointedly at his lunch.

"Fork'em over Sans!" Red smirked at him.

"I would like to see too." Toffee hummed looking over at Sans who was sweating lightly.

“B-but- I - it's - No!” Sans squeaked, jumping to his feet and stumbling back. “They’re mine!”

"Aw, we won't keep them Sans!" Stretch cooed grabbing him around the waist and tugging him into his lap. "Just a peek!"

“Hey!” Sans cried out as he was pulled. Darn papyruses and their freakish heights! 

“Easy, Sansy. Let us see!” Red said.

"It was really cute what they wrote about Sans!" Blue giggled looking amug.

“F-fine I’ll share one…” Sans said, blushing brightly.

"Make it a good one eh?" Stretch teased setting him down.

Sans squinted at him, pulling out the first note, gingerly handing it to Stretch, it was precious, and he didn’t want it to get damaged. If Stretch wasn't careful with it, he was going to have a bad time.

Stretch took it and read it over his grin growing before handing it off to Red next.

Red took it and smirked. "Ain't this rich? Ya got someone lookin' fer more than a quick fuck. That’s fuckin adorable."

Toffee snagged it next and he smiled softly, giving it back to Sans. "That's very sweet, I hope you'll be able to find out who it is Sans."

"Blue was supposed to be doing some recon on that." Sans said, still blushing as he gently put the butterfly back in his inventory.

"And I did! But no one seems to know anything." Blue crossed his arms and pouted slightly. "Or they're hiding what they know."

"That's okay, I'll be meeting them tonight." Sans admitted with a shy smile.

"What?! You will? When?!" Blue gasped no longer pouting as he grabbed Stretch by the arm shaking his brother in excitement.

“Tonight. We’re going to meet.” Sans admitted, soul summersalting in his ribcage. “According to the letter."

"I wanna see!" Red came forward looming over Sans. "Hand it over shrimp!"

Sans blushed harder, he didn’t want a bunch of crashers in on their meeting. He wanted to meet whoever was sending him these amazing notes by himself! “T-tomorrow.” Sans said.

"Why t'morrow?" Red demanded crossing his arms.

"Now Red don't pry, it's none of our business! Sans will share when he's ready, he's already shared one with us!" Toffee scolded wagging a finger at Red.

Red huffed, eyelights scanning Toffee over in amusement. “But I wanna read it.” 

"He doesn't want you to." Toffee deadpanned, hands on his hips.

“Aint fair.” Red replied, grinning, his gold tooth flashing.

"Life isn't fair. Now shoo, you've got a class soon don't you?" Toffee quirked a brow bone at Red.

Red gave Toffee a petulant look, leaning against him. “Nah, I’m playin’ hookie.”

"I'll inform your brother of your choice then." Toffee mused.

“What!?” Red said eyelights shrinking. “Nah, ya don’t gotta do that!” He spluttered as Sans snorted.

"Why not?" Toffee asked, raising a brow bone at Red.

"Cuz Edgelord'll kick his ass." Stretch snickered digging through Sans's pockets. "Just a peek!"

"Stretch no!" Sans squeaked, wriggling away and covering his pockets. "It's mine!"

"Papy that's rude!" Blue scolded giving Stretch a stern look.

"Aw, but bro, it's so precious, I wanna see the others." Stretch said innocently.

"No! Bad Papy!" Blue continued to scold, tugging him away from Sans.

Stretch pouted, but let himself be pulled, becoming deadweight in Blue’s arms, sinking against the picnic blanket. Red meanwhile, was doing his best to give Toffee an innocent look.

Toffee took out his phone and began to text someone, humming quietly.

"...Yer not texting boss, right!?" Red asked, beginning to sweat.

"Better get your coccyx to class, Red, before Edgelord comes and 'escorts' you." Sans sniggered.

Toffee paused as his phone went off, answering it. "Hello Edge, yes, he's right here. Do you want to speak with him?"

Red groaned. “Ya traitor!” He gave Toffee a wounded look.

"You're on speaker Edge." Toffee said holding his phone aloft.

"Sans!" Edge barked through the phone.

Red grimaced. “Well would ya look at the time, gotta go!” Red quickly stood up, about to shortcut away when Sans grabbed his hood pulling him back down.

“Now, now, wouldn’t want you missing a conversation with your little bro. Family’s important.” Sans said with a vicious grin.

"What is this I'm hearing about you skipping class?!" Edge demanded loudly, so much so they wondered if he even needed to be on speaker to be heard.

Red looked like a deer in headlights, looking around for help or an escape. “Nothin’ Bro! Was just talking shit.” Red said.

“Well get your coccyx to class then!”

“I’m eating! It ain't time yet anyway.” Red gruffed.

Toffee made it a point to show Red what time it was, he had five minutes to get to class. "Really Sans! I know you're lazy but even you can read a clock!" Edge scolded.

Red grumbled, stuffing his sandwich in his face and standing up. He gave both Toffee and Sans the evil eye for their participation in thwarting his skipping class plan. “I’m goin’ I’m goin’! Killjoys.” 

"You better Sans!" Edge scowled from over the phone.

"It's not our fault you wasted all your time instead of eating." Toffee retorted.

“Yeah, yeah.” Red grunted, sticking his tongue out before heading off to class. Sans frowned at his own phone. He’d better get going soon, too.

"Well, I suppose I should get going." Toffee mused. "I need to finish up my homework for tomorrow."

“Alright, later Toff. Hope your date mate gets to class.” Sans winked.

"I don't have one Sans." Toffee sighed at him, waving as he left.

Sans raised a brow bone and looked to Stretch and Blue. “You mean they’re still not dating?”

"Not for lack of trying on Red's end." Stretch snorted.

“Huh.” Sans said. “Damn. Fifty G they’ll be dating by next month.” Sans gave the swap brothers a grin.

"Toff will beat your coccyx if he found out you were betting on his love life." Stretch snickered. "You're on."

“He’s just pent up. Needs a good fucking, that Red can provide.” Sans sniggered and Blue scoffed squinting at the two. “Come on, Blue. You in?”

Blue was holding a book that looked suspiciously like a bondage manual that had the dating manual cover over top. "What's that Sans?" He looked over.

“How much gold on Toffee and Red’s love life.” Sans said, picking up his trash, raising a brow bone at his friend. “Stretch, your brother is a perv.”

"Oh! Hmmm...well, depends. Are we betting on them being together or someone else stepping in?" Blue asked, closing his book.

“Who would step in? And what do you mean Sans?” Stretch asked curiously and Sans hummed. 

“Know something we don’t? And his BDSM book, Stretch, duh.” 

"Maybe I do, maybe I don't." Blue replied, stashing the book for now. "I bet fifty gold Toffee ends up with someone else."

“Oh?” Sans asked with a grin. “Deal. Now I gotta get to class too, before my own brother notices I’m late.” He would eat his lunch on the way.

"Cya Sans!" Blue waved cheerily, smiling wide.

***

Sans knew he'd be nervous to meet his secret admirer but he hadn't thought he'd be  _ this _ nervous! After stressing over what to wear he defaulted to his normal clothing, it wasn't a formal event and whoever it was knew what to expect from him already. That being minimal effort when it came to his appearance. Sans stood under a nearby tree trying not to chicken out and just run away entirely, because that would be easier.

He took a deep breath, wringing his hands together, soul pounding. He should go, go before the secret admirer comes. It’d be so much easier - what if they didn’t like him? What if it was a cruel trick? What If they'd brought him out here just to humiliate him, or-

"Heya Sans." Called a familiar low voice, Slim was a few feet away smiling lazily at Sans.

Sans’s cheekbones flushed a deep indigo. So Slim was his secret admirer- or- or, stars, what if Slim just happened to be here by circumstance!? No, that was ridiculous!

"What's goin on?" Slim purred coming closer, he spotted his brother approaching. A grin spread across his face when Razz stopped and glared at him from behind Sans before scowling and turning to go another way.

Sans saw Slim’s grin, and having no idea Razz was retreating behind him, took a step closer to Slim. Of course Slim had written the notes, why else would he be here? Why else would Slim have been talking to him lately? “Just came to look at the stars before the meteor shower.” Sans said with a wink.

"Oh yeah?" Slim looked down at Sans, so much like his brother yet so very different. He hummed and leaned his back against the tree trunk, looking up. "Stars are pretty bright tonight, but you shine even more."

Sans blushed even brighter, so Slim  _ was _ his admirer. He didn’t know what to say. He thought Slim had just been being friendly, he didn’t realize Slim had an actual interest in him. “U-uh, I don’t know about that, but thanks…” Sans said shyly.

"So, you here all alone?" Slim asked, tugging out a lighter and pack of cigarettes. He winked at Sans as he stuck one between his teeth, lighting it up.

Sans still blushing, nodded. “Well, not anymore.”

"I guess that's true." Slim laughed softly looking around as more monsters gathered around to use the telescopes. Spotting Razz again who looked to be pouting, he reached over carefully wrapping an arm around Sans's shoulders. Razz’s pout deepened, and he crossed his arms, kicking a rock.

Sans was quite certain his entire skeletal system was glowing blue at this point, his soul pounding in his chest. He never would have thought Slim liked him like this, or saw anything in him.

"You wanna look at the stars?" Slim asked, pulling Sans to his side and looking down at him with a wolfish grin. "Because I'm looking at one now."

Sans’s eyelights shrank, and he sputtered completely caught off guard. Who knew Slim was so smooth!? How was he supposed to reply to that? He couldn’t help but feel flattered, soul pulsing warmly in behind his ribcage. “H-heh, think ya need your sockets checked.” Sans said.

"Oh yeah?" Slim leaned down closer so they were a mere breath apart, looking into one another's sockets. "How bout you check'em for me?"

Sans squeaked and couldn’t help but look into the other skeleton’s eyelights. They were white, like his own Papyrus’s, lit with amusement and joy. Had Sans made him feel that way?

"Maybe I do need'em checked, after looking at a star so bright for so long." Slim took the lit cig from his mouth and leaned even closer, their teeth nearly touching. His breath warm against Sans teeth, he smelled like smoke and pine.

Sans was completely captivated, hanging onto every word Slim said. Stars, he was like a damn teenager, Slim’s sweet talking going straight to his soul. No one had ever said such nice things about him. He wasn’t anything special, but. . . Slim thought he was. Sans leaned forward, pressing his teeth against Slim’s.

Slim hadn't actually expected Sans to act, his arm tightened around Sans's back and he pressed closer. Kissing Sans back, at the same time he caught his brother's gaze. Holding it even as he continued to kiss Sans, noting how angry he looked.

Razz scowled, watching the two of them, his hands balled into fists as Sans began to kiss his brother. His hands trembled and he tore his gaze from the pair after Slim caught his gaze, storming off by himself. Ignoring the burn in his sockets.

**Notes for the Chapter:**

> Chaos: [Slim](https://www.youtube.com/watch?v=lX44CAz-JhU) is smooth, but he sure as hell isn't sweet.
> 
> Zion: Was this a fated meeting, or a happenstance one?
> 
> Chaos: I know nothing; I'm Jon Snow.


End file.
